Ischemia in wound healing. II: Design of a flap model--biomechanical properties.

A standardized reproducible H-shaped double flap model for biomechanical testing of ischemic wounds was developed in rats. After 10 days of healing all the biomechanical parameters of the flap wounds decreased significantly, compared with normal healing incisional wounds. After 20 days of healing the extensibility as well as the most important biomechanical parameters were still significantly decreased. In part I of this study we showed that on day 1 the blood flow had decreased to 7% of the flow in normal incisional wounds, though it returned to normal on day 16. Here we show that this drop in blood flow results in a significant decrease in all the biomechanical parameters and thereby caused significant delay in the healing of the test wounds. There was no correlation between any of the biomechanical parameters and the length of surface necrosis on the flaps. These necroses thus do not necessarily reflect necrosis of the dermis, where the healing is responsible for the continuity and strength of the skin.